Extracting And Applying Chitin In Antarctic Krill Shell

Antarctic krill have been found to be one of the most resource-rich and largest aggregated multicellular animals in the world so far, and they are the greatest enzyme producer in digesting proteins. They have large quantity, abundant nutrients as well as widespread use, which make them receive increasingly interest and become a hot topic in the research field in recent years. The meat of Antarctic krill can be used to bait fish, to extract high-quality deep sea fish oil, to make drug for heart conditions, and to eat by human and many other animals. The shell of Antarctic krill can be used to extract chitin because the content of chitin in Antarctic krill is much higher than other marine shelled organisms which account for around28.73%according to the experiment.Chitin, which exists as high polymer and amino polysaccharide, is a sort of environment friendly and reproducible natural resource, whose reserves in the world is next to cellulose, and it is widely found in cell walls of insects, aquatic shrimp and crab, crustaceans, fungi and algae. It is also the only but large existed natural basic polysaccharide. Pure chitin is subtransparent in white or grayish white with non-toxic and odorless and is difficult to dissolve in water, diluted acid, diluted alkali and general organic solvent. Chitin and its derivatives chitosan are called the sixth basic ingredients of life by scientists. They have unique functions and characteristics which are used in a wide range of applications, such as environmental protection, food, medicine, functional materials, textile industries and so on. As a result, they have great economic value and broad application prospects.In this paper, compositions of Antarctic krill shell were analysed first. Then chitin was extracted from Antarctic krill by traditional acid and alkali method. After testing by orthogonal experiment, the optimum process conditions were confirmed. Finally, the methods of making up chitosan were researched. By a series of researches, the advantages, efficiency and process conditions should all be found out. The results can also be used to provide reference for extracting chitin by bioanalysis.The main contents of this paper include:1. Two samples, Antarctic krill and Alaska snow crab, were chosen first to contrast their shell compositions by component analysis. According to the experiment, after4hours’ stoving under65℃, there is3.26%water,16.33%ash,12.46%fat,39.22%crude protein and28.73%chitin in shell of Antarctic krill. At the same time, there is2.19%water,35.65%ash,6.63%fat,33.96%crude protein and21.57%chitin in shell of Alaska snow crab. It can be found out that the shell of Antarctic krill is more considerable because of its higher content of chitin. 2. Different experiment schemes were chosen to process the krill shell, through orthogonal experiment, the most tightly linked factors in extracting chitin were found and how each factor affect the treatment process were analyzed. The factors are concentration of sodium hydroxide solution and hydrochloric acid solution, temperature, processing time, krill shell powder and solid-liquid ratio. The optimum process conditions are:alkali treatment: concentration25%, solid-liquid ratio1:10, temperature95℃,2hours; acid treatment: concentration10%, solid-liquid ratio1:10, temperature60℃,2hours. By this way,94.254%high-purity chitin was produced. And other components are0.38%ash,0fat and5.366%crude protein.3. During the experiment the grinding degree of shell was also found out to have a great influence on the chitin’s extraction efficiency, and after testing, it is confirmed that the conclusion that the material’s fineness should be within forty mesh.4. The chitosan was gotten through the process conditions as follow:alkali treatment: concentration50%, temperature95℃and3hours. The deacetylation of chitosan was tested to be87.5%, the viscosity of it was152.5mPa.s and the chitosan can dissolve in1%acetic acid.5. According to the SEM and infra-red spectrogram of different steps and the characterization method of chitin, the quality and properties of chitin and chitosan product can be analyzed.